About High Availability

Process restartability provides the high availability functionality in Cisco MDS 9000 Family switches. This process ensures that process-level failures do not cause system-level failures. It also restarts the failed processes automatically. This process is able to restore its state prior to the failure and continues executing from the failure point going forward.

An HA switchover has the following characteristics:

It is stateful (nondisruptive) because control traffic is not impacted.

It does not disrupt data traffic because the switching modules are not impacted.

Synchronizing Supervisor Modules

The running image is automatically synchronized in the standby supervisor module by the active supervisor module. The boot variables are synchronized during this process.

The standby supervisor module automatically synchronizes its image with the running image on the active supervisor module.

Note The image a supervisor module is booted up from cannot be deleted from bootflash. This is to ensure that the new standby supervisor module ia able to synchronize during the process.

Manual Switchover Guidelines

Be aware of the following guidelines when performing a manual switchover:

When you manually initiate a switchover, system messages indicate the presence of two supervisor modules.

A switchover can only be performed when two supervisor modules are functioning in the switch.

The modules in the chassis are functioning as designed.

Manually Initiating a Switchover

To manually initiate a switchover from an active supervisor module to a standby supervisor module, use the active supervisor module using Device Manager
system switchover
command. After you enter this command, another switchover process cannot be started on the same switch until a stable standby supervisor module is available.

To ensure that an HA switchover is possible, enter the
show system redundancy status
command or the
show module
command. If the command output displays the HA standby state for the standby supervisor module, then the switchover is possible. See "Verifying Switchover Possibilities" for more information.

To perform a switchover using Device Manager, follow these steps:

Step 1 Ensure that an HA switchover is possible by selecting Physical > Modules to verify the presence of multiple modules.

The Status column in the output should display an OK status for switching modules and an active or HA-standby status for supervisor modules. If the status is either OK or active, you can continue with your configuration.

Use the
show boot auto-copy
command to verify the configuration of the auto-copy feature and if an auto-copy to the standby supervisor module is in progress. Sample outputs of the
show boot auto-copy
command follow:

switch# show boot auto-copy

Auto-copy feature is enabled

switch# show boot auto-copy list

No file currently being auto-copied

Copying Boot Variable Images to the Standby Supervisor Module

You can copy the boot variable images that are in the active supervisor module (but not in the standby supervisor module) to the standby supervisor module. Only those KICKSTART and SYSTEM boot variables that are set for the standby supervisor module can be copied. For module (line card) images, all boot variables are copied to the corresponding standby locations (bootflash: or slot0:) if not already present.

Enabling Automatic Copying of Boot Variables

To enable or disable automatic copying of boot variables, follow these steps:

Verifying the Copied Boot Variables

Use the
show boot auto-copy
command to verify the current state of the copied boot variables. This example output shows that automatic copying is enabled:

switch# show boot auto-copy

Auto-copy feature enabled

This example output shows that automatic copying is disabled:

switch# show boot auto-copy

Auto-copy feature disabled

Use the
show boot auto-copy list
command to verify what files are being copied. This example output displays the image being copied to the standby supervisor module's bootflash. Once this is successful, the next file will be image2.bin.

Note This command only displays files on the active supervisor module.

switch# show boot auto-copy list

File: /bootflash:/image1.bin

Bootvar: kickstart

File:/bootflash:/image2.bin

Bootvar: system

This example output displays a typical message when the
auto-copy
option is disabled or if no files are copied:

switch# show boot auto-copy list

No file currently being auto-copied

Displaying HA Status Information

Use the
show system redundancy status
command to view the HA status of the system. Tables
7-1 to
7-3 explain the possible output values for the redundancy, supervisor, and internal states.

switch# show system redundancy status

Redundancy mode

---------------

administrative: HA

operational: HA

This supervisor (sup-1)

-----------------------

Redundancy state: Active

Supervisor state: Active

Internal state: Active with HA standby

Other supervisor (sup-2)

------------------------

Redundancy state: Standby

Supervisor state: HA standby

Internal state: HA standby

The following conditions identify when automatic synchronization is possible:

If the internal state of one supervisor module is Active with HA standby and the other supervisor module is HA standby, the switch is operationally HA and can do automatic synchronization.

If the internal state of one of the supervisor modules is none, the switch cannot do automatic synchronization.